Cylinder breech mechanism for small arms

ABSTRACT

A firearm includes a receiver, a barrel, a bolt slidable in the receiver, spreaders mounted in the bolt for being pivoted into a locking recess on the receiver and a locking element for shifting the spreaders. The locking element includes rotatable spreader cams to extend the spreaders in response to rotation of the locking element in one direction, and includes unlocking cams operable to engage and shift the spreaders to a retracted position in response to rotation of the locking element in the opposite direction. A latch is provided to prevent the locking element from rotating relative to the bolt when the bolt is withdrawn from the receiver.

United States Patent Bielfeldt, deceased et al.

1451 Sept. 17, 1974 [54] CYLINDER BREECH MECHANISM FOR 2.730.928 l/1956 S21etterLassen 89/190 SMALL ARMS 2,948,195 8/1960 Linder 89/190 3.707 795 1/1973 Bielfeldt 42/16 [75] Inventors: Heinz Bielfeldt, deceased, late of Eckernforde, Germany Gerlinde P E A B h It Bielfeldt, heir; Christiane Diehl, on 6 Karste" q Eckemforde Attorney. Agent. or Firm-Burns, Donne. Swecker & both of Germany heirs Mathis [73] Assignee: J. P. Sauer & Sohn GmbH,

Eckernforde, Germany [57] ABSTRACT [22] Filed: Apr. 26, 1973 A firearm includes a receiver. a barrel, a bolt slidable in the receiver, Spreaders mounted in the bolt for [21] Appl 354774 being pivoted into a locking recess on the receiver and a locking element for shifting the Spreaders. The loc k [30] Foreign Application Priority Data ing element includes rotatable spreader cams to ex- June 7 1972 Germany 2227780 tend the Spreaders in response to rotation of the locking element in one direction, and includes unlocking 52 US. Cl. 42/16, 89/190 Cams operable to engage and shift the Spreaders to a 51] Int. Cl F411: 11/06, F4ld 3/00 retracted Position in response to rotation of 109k- [58] Field of Search .1 42/16; 89/190 ing element in the Opposite direction A latch is P vided to prevent the locking element from rotating rel- 5 References Cited ative to the bolt when the bolt is withdrawn from the UNITED STATES PATENTS 2,601,808 7/1952 Clarke 89/190 14 Claims, 5 Drawing Figures Pmmmswnw 3.835.566

SHEEI 1 OF 2 FIG.1

PAIENIEU SH! 1 Ian SHEET 2 OF 2 CYLINDER BREECH MECHANISM FOR SMALL ARMS BACKGROUND AND OBJECTS OF THE INVENTION The invention relates to a cylinder breech block mechanism for small arms. Of particular concern is a breech casing or receiver portion in which a locking element is movable by means of a bolt handle which is guided in a slot of the receiver. The locking element locks the body of the bolt by means of at least one spreader which is pivotal radially from a withdrawn to a locking, spreading position and which extends essentially in the longitudinal direction of the bolt. The spreader is supported by the bolt and is rotatable into an indentation in the receiver.

One form of such breech mechanism is disclosed in U.S. Pat. No. 2,601,808 and utilizes an axial shifting of the ramp surfaces of a locking element relative to the body of the bolt to spread the spreaders in order to lock the bolt relative to the receiver. The spreaders, whenever they are underrun by the ramp surfaces, are swung into supporting indentations in the inside wall of the receiver by the suitable ramp surfaces on the locking element. Engagement between the surfaces of the indentations and corresponding countersurfaces of the spreaders serves to transfer the recoil from the bolt to the receiver. For the purpose of spreading the spreaders an axial relative shifting of the locking element and the bolt is therefore necessary, which shifting requires a certain additional overall bolt length. Moreover, the swinging of the spreaders into their ineffective or nonlocking position is accomplished by means of the power of a spring or by a special corresponding slope of the engaging supporting surfaces of the indentations and spreaders, whereby the former means has the disadvantage that the reliability of operation may suffer by fatigue of the spring, and the latter means results in a less reliable transfer of the force of the recoil to the receiver.

A general object of this invention is to obviate or minimize the problems discussed above.

A particular object of the invention is to provide a breech mechanism which may be locked independently of axial movement of the bolt.

A further object of the invention is to improve the operation of the spreaders of a breech mechanism in a way which minimizes the overall length of bolt required.

A further object of the invention is to provide means for retracting the spreaders independently of the indentation surfaces and special spring devices. According to this objective, the in-and-out swinging of the spreaders is to be free of any accidental causes, i.e., it is to be precisely controlled. Any possible disturbances of operation as a result of poor gliding on slanted surfaces of the locking recess or fatigue of return springs, or similar things, are to be eliminated.

BRIEF DESCRIPTION OF THE INVENTION The achievement of these objects is accomplished through the provision of a locking element which is operably connected to the bolt. The locking element includes means for spreading the spreaders in response to rotation of the locking element. The locking element also includes means for positively engaging and retracting the spreaders.

The locking element includes a neck piece projecting into the bore of the bolt penetrated by the firing pin. The neck piece is surrounded by the bolt and is rotatable relative thereto. The neck piece includes spreader cams operable to push a plurality of spreaders into the spreading position and support the spreaders in such position, in response to shifting of the bolt handle to its locking swivel position. The spreading cams are defined by a surface of the neck piece, the latter including idented sections on its periphery between the spreader cams for reception of the spreaders swung into the ineffective position.

The neck piece also carries unlocking cams which are circumferentially offset relative to the spreader cams and which are operable to engage and shift the spreaders to a withdrawn position.

THE DRAWING The invention is explained even more exactly with additional advantageous developments and in connection with the drawing on the basis of an embodiment given by way of example.

FIG. 1 shows a perpendicular longitudinal section through a breech mechanism of the invention in its closed or locked state;

FIG. 2 shows the same perpendicular longitudinal cut, in which the spreader locking is de-activated in response to the bolt handle being shifted by about 65 as compared to FIG. 1;

FIG. 3 shows a cross section along line 33 in FIG.

FIG. 4 shows a section in perpendicular longitudinal section through the bolt and the locking element while the bolt is pulled out of the receiver; and

FIG. 5 shows a cross section taken along the line 5-5 in FIG. 2.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT In the figures, the breech casing or receiver is given the reference number 11, the bolt is 12, the locking element is 13 and the bolt handle is designated by 14. The locking element is rotatable around the axis of the barrel by handling of the attached bolt handle 14. Moreover, the locking element 13 is longitudinally slidable in the receiver 11 together with the bolt 12. The customary inside bore, which is constant in its diameter, goes through the receiver. The rear end of the bolt 12 is provided with indentations or recesses for the reception and mounting of tangs or spreaders 15, the spreaders being pivotally mounted on the bolt by means of hinge pegs 16. The pegs 16 are disposed perpendicularly on cross-sectional diametric planes and are arranged at the swivel center of the pivot spreaders 15, whereby, the transfer of force of the spreaders does not take place by way of the pegs 16, but by means of the mutually engageable bearing surfaces of the locking recess and the spreaders. As will be subsequently explained, the spreaders 15 are operated by the locking element 13.

The front end of the locking element comprises a long neck piece 17 having a smaller diameter and is disposed in a longitudinal bore of the bolt which is dimensioned correspondingly and through which the firing pin 18 passes. The neck 17 of the locking element and bolt 12 are fixed relative to one another axially by means of a suitable bayonet-type catch so as to accomodate relative rotation therebetween. The bayonet catch, illustrated in FIG. 5, comprises a cam extension 31 of the neck 17 which projects outwardly beyond the periphery of the neck. This cam extension 31 is rotatable within a groove 30 carried by the bolt 12. This groove is positioned and dimensioned such that the locking element 13 can be pivoted relative to the bolt 12, within its normal pivot region limited by the receiver 11, without the occurrence of relative axial displacement between the bolt 12 and the locking element 13. A longitudinally, or axially, extending groove 30a is provided in the inner wall surface of the bolt 12. This groove 30a is angularly displaced by an amount sufficient to insure that during normal use of the cylinder breech mechanism the cam 31 will not be able to enter this axial groove 30a. The axial groove 30a allows relative assembling and disassembling of the bolt 12 and the locking element 13. The groove 30a is arranged in relation to the normal pivot region of the bolt 12 such that the bolt 12 and the locking element 13 must be withdrawn from the receiver 11 in order to allow the cam 31 to be displaced angularly more than during its normal pivoting to bring the cam 31 into axial alignment with the axial groove 30a.

In the rear part of the neck of the locking body, which in the case of an assembled breech mechanism is located radially inside the spreaders 15, are provided spreader cams 19 (FIGS. 1 and 3). The spreader cams 19 correspond in number to spreaders l and correspond to their distribution or positioning on the periphery. In the case of the embodiment shown by way of example there are three evenly spaced spreader cams with three evenly spaced spreaders, the spacing between the spreaders being the same as the spacing between the cams. Between the cams 19 are disposed indented grooves or sections 19a with transitional gliding surfaces 19b located between and interconnecting the indented sections and the spreader cams.

In the area of spreaders 15, and especially in the area of their ends, an annular groove or recess 20 has been cut into the cylinder wall of the receiver 11. The annular groove includes an acute conical front part 20a. which permits the spreading of spreaders within the receiver bore. An essentially more truncated conical rear section b of the annular groove serves as the supporting surface for the terminal surfaces of spread ers 15 whenever the latter are spread.

FIG. 3 clearly shows the arrangement of the spreader cams in the case of three spreaders l5 distributed evenly on the periphery. In FIG. 3, furthermore, it can be recognized that a control disk 21 in top view, which, as can be recognized from the longitudinal section of FIGS. 1 and 2, has a crank-like recess 21a on its side facing the spreaders and which is connected to the locking element with torsional strength and moreover is fixed axially therewith. In other words, the control disk 21 is arranged to rotate with and be axially shifted with the locking element. Rear projections 15a of the spreader extend into the recess 21a of control disk 21, whereby a mutual, circumferentially offset or staggered arrangement of control disk 21 relative to the spreader cams of the neck 17 of the locking element is such that projections 15a will enter into the recess areas 21a and will be projected further radially outwards within these recesses whenever the spreaders are spread by the spreader cams 19. In the case of twisting the locking element by about 65 by means of bolt handle 14, the spreaders are forcefully swung out of lock groove 20 of the bolt as a result of their guidance on the marginal surface 21c of recess 21a and with the aid of cam-like control projections 21b of the control disk pointing inwardly, and are swung radially inwards toward the neck of the locking element body.

In the rear area of receiver 11 there is a bolt catch lever 22 mounted pivotally on a cross pin 23 and coupled with the triggering device (not shown) in conventional fashion. The upper part 22a of the bolt catch lever extends into a longitudinal groove 28 of body 12 of the bolt and, as a result, the bolt can move only axially relative to the receiver but it cannot rotate relative thereto with the catch lever in the position shown in FIG. 2.

In the front section of neck 17 of the locking body there is a longitudinal groove 24 (see FIG. 4) on a place of the periphery. The groove faces a catch 26 pivotal about an axis comprising a hinge pin 25. The catch stands perpendicularly relative to a diametric plane through the bolt, in the case of the relative position of the locking element and the bolt where the spreaders are swiveled inwardly. This latch is spring loaded at one end by means of a compression spring 27 so that its rear end. whenever the bolt is pulled axially from the receiver 11, can swing outwardly (FIG. 4). In this manner, the front end of the latch swings inwardly into groove 24, as a result of which, relative rotation between the locking element 13 and the bolt 12 will be prevented in the open state of the breech. As a result the spreaders 15, which are under forced, retracted control as a result of the rotation of bolt handle 14 and disk 21, will be prevented from spreading while the breech is opened. Spreading at this time could lead to a functional disturbance in the breech in the case of a renewed closing of the bolt.

OPERATION In FIG. 1, the completely closed locked breech is shown. It is desirable, however, to explain the closing process first of all beginning with the position according to FIG. 2, in which the breech bolt has already been pushed shut but has not yet been locked. This locking is accomplished by a downward swiveling of bolt handle 14 by about 65, whereby the bolt handle is guided in a conventional guide slot of the receiver 1 1. Locking element 13 is turned with the bolt handle, so that the spreading cams 19 carried by neck 17 of the locking element are turned to a position below the spreaders 15 and will cam the latter outwards into annular groove 20 by means of the slanted transition surfaces 19b.

The force exerted during recoil on bolt 12 is transferred to the receiver 11 by way of the spreader elements being in almost axial alignment and by way of the relatively large supporting surfaces of the spreader elements.

Upon opening the breech, the movements take place in a reverse sequence, with the handle 14 being raised. Control disk 21 now acts with the marginal surface 21c of its recess 21a and with projections 21b to exert an inward force on the projections 15a of the spreaders to pivot the latter inwardly. After completion of the 65 turning movement of the locking element to force the spreaders l5 completely out of groove 20, the locking element can then be withdrawn from the receiver together along with the bolt so that, for example, an additional cartridge can be moved into the barrel. As soon as the rear end of latch 26 emerges during this time from the bore of receiver 11, its front end will be forced into groove 24 of the neck of the locking element and will prevent mutual turning of bolt 12 and element 13 of the breech mechanism. During the pushing in of the breech bolt, latch 26 is again pivoted out of the longitudinal groove 24 automatically by the wall of the bore of receiver 11 and counter to the force of spring 27.

MAJOR ADVANTAGES AND SCOPE OF THE INVENTION Due to the fact that the present invention provides a rotatable, rather than axially shiftable, cam 19, 19b for spreading the spreaders, the bolt may be designed with reduced overall length.

With the provision of means 21 for positively shifting the spreaders to a retracted state, there is no need to provide springs or a special cam surface arrangement between the spreaders and locking recess to cause the spreaders to be shifted inwardly in response to the bolt being pulled back. Such a special cam surface arrangement tends to present a less efficient transfer of force from the bolt to the receiver and necessitates the use of additional locks such as at 45 in the afore-mentioned US. Pat. No. 2,601,808. Thus, the surface arrangement between spreaders and the groove b according to this invention may be designed for optimum transfer of forces.

Although the invention has been described in connection with a preferred embodiment thereof, it will be appreciated by those skilled in the art that additions, modifications, substitutions and deletions not specifically described may be made without departing from the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. In a firearm having a receiver, recess means carried by said receiver, bolt means slidably mounted in said receiver, a firing pin extending through a bore in said bolt means, at least one spreader pivotally mounted at one end to said bolt means and extending generally longitudinally of said bolt means, said spreader being pivotal radially from an inward, withdrawn position to an outer locking position within said recess means, and means for shifting said spreader comprising:

a locking element operably connected to said bolt means;

handle means operably connected to said locking element and movable within a slot carried by said receiver to afford rotation of said locking element relative to said bolt means;

said locking element including rotatable neck means projecting into the bore of said bolt means and being enveloped by and rotatable relative thereto;

said rotatable neck means carrying at least one spreading cam and at least one indented section adjacent said spreading cam;

said spreading cam and indented section being arranged such that, in a closed position of said bolt means, rotation of said neck means to a locking posture causes said spreading cam to extend said spreader into said recess means and support said spreader therein, and rotation of said neck means to an unlocking posture affords reception of said spreader within said indented section.

2. In a firearm according to claim 1 wherein said spreader is pivotally connected to and retained by said bolt means by a pivot pin.

3. In a firearm according to claim 1 wherein said spreader, at the other end thereof, includes a projection; said locking element including a control surface engageable with said projection to retract said spreader from said recess means.

4. In a firearm according to claim 3 wherein said locking element includes a control disk; an inside cam surface of said control disk constituting said control surface and over-reaching said projection in a closed position of said bolt means; said inside cam surface including at least one unlocking cam disposed in circumferentially offset relation to said spreader cam.

5. In a firearm according to claim 4 wherein said neck means carries three evenly spaced spreading cams and three evenly spaced indented sections, and said inside cam surface carries three evenly spaced unlocking cams.

6. A firearm according to claim 1 wherein said bolt means is connected to said locking element for axial shifting movement therewith.

7. A firearm according to claim 3 wherein said bolt means is connected to said locking element for axial shifting movement therewith.

8. A firearm according to claim 1 and further including a latch pivotally carried by a pivot pin in a recess of said bolt means; said neck means carrying a slot; spring means for pivoting said latch into said slot, with said bolt means in an open position, to lock said bolt means and said locking element against relative rotation; said latch being disposed out of said slot in a closed position of said bolt, through the action of said receiver acting thereon, to accomodate relative rotation between said locking element and said bolt means.

9. A firearm according to claim 3 and further including a latch pivotally carried by a pivot pin in a recess of said bolt means; said neck means carrying a slot; spring means for pivoting said latch into said slot with said bolt means in an open position to lock said bolt means and said locking element against relative rotation; said latch being disposed out of said slot in a closed position of said bolt through the action of said receiver acting thereon, to accomodate relative rotation between said locking element and said bolt means.

10. A firearm comprising:

receiver means including locking recess means; barrel means secured to said receiver means;

bolt means slidably mounted in said receiver means;

at least one spreader tang carried by said bolt means and arranged for shifting movement between: a locking position wherein a portion of said spreader tang is disposed in said recess means to lock said bolt means against axial movement, and

a non-locking position wherein said spreader tang is free of said locking recess means; and tang-operating means rotatable relative to said bolt means and being arranged to shift said bolt means axially;

said tang-operating means including means for shifting said spreader tang into said locking position in response to rotation of said tang-operating means in one direction.

11. A firearm according to claim 10 wherein said means for shifting comprises a rotary cam surface carried by said tang-operating means.

12. A firearm according to claim 10 and further including means for engaging and moving said spreader tang from said locking position to said unlocking position in response to rotation of said tang-operating means in the opposite direction.

13. A firearm according to claim 12 wherein said means for engaging and moving comprises an auxiliary rotary cam surface carried by said tang-operating means.

14. A firearm comprising:

receiver means including locking recess means;

barrel means secured to said receiver means;

bolt means slidably mounted in said receiver means;

at least one spreader tang carried by said bolt means and arranged for shifting movement between;

a locking position wherein a portion of said spreader tang is disposed in said recess means to lock said bolt means against axial movement in said receiver means, and

a non-locking position wherein said spreader tang is free of said locking recess means; and

tang operating means mounted for rotation relative to said tang and including:

first cam surface means for engaging and shifting said spreader tang into said locking position in response to rotation of said tang operating means relative to said tang in a first direction; and

second cam surface means for engaging and shifting said spreader tang into said non-locking position in response to rotation of said tang operating means relative to said tang in a second direction 

1. In a firearm having a receiver, recess means carried by said receiver, bolt means slidably mounted in said receiver, a firing pin extending through a bore in said bolt means, at least one spreader pivotally mounted at one end to said bolt means and extending generally longitudinally of said bolt means, said spreader being pivotal radially from an inward, withdrawn position to an outer locking position within said recess means, and means for shifting said spreader comprising: a locking element operably connected to said bolt means; handle means operably connected to said locking element and movable within a slot carried by said receiver to afford rotation of said locking element relative to said bolt means; said locking element including rotatable neck means projecting into the bore of said bolt means and being enveloped by and rotatable relative thereto; said rotatable neck means carrying at least one spreading cam and at least one indented section adjacent said spreading cam; said spreading cam and indented section being arranged such that, in a closed position of said bolt means, rotation of said neck means to a locking posture causes said spreading cam to extend said spreader into said recess means and support said spreader therein, and rotation of said neck means to an unlocking posture affords reception of said spreader within said indented section.
 2. In a firearm according to claim 1 wherein said spreader is pivotally connected to and retained by said bolt means by a pivot pin.
 3. In a firearm according to claim 1 wherein said spreader, at the other end thereof, includes a projection; said locking element including a control surface engageable with said projection to retract said spreader from said recess means.
 4. In a firearm according to claim 3 wherein said locking element includes a control disk; an inside cam surface of said control disk constituting said control surface and over-reaching said projection in a closed position of said bolt means; said inside cam surface including at least one unlocking cam disposed in circumferentially offset relation to said spreader cam.
 5. In a firearm according to claim 4 wherein said neck means carries three evenly spaced spreading cams and three evenly spaced indented sections, and said inside cam surface carries three evenly spaced unlocking cams.
 6. A firearm according to claim 1 wherein said bolt means is connected to said locking element for axial shifting movement therewith.
 7. A firearm according to claim 3 wherein said bolt means is connected to said locking element for axial shifting movement therewith.
 8. A firearm according to claim 1 and further including a latch pivotally carried by a pivot pin in a recess of said bolt means; said neck means carrying a slot; spring means for pivoting said latch into said slot, with said bolt means in an open position, to lock said bolt means and said locking element against relative rotation; said latch being disposed out of said slot in a closed position of said bolt, through the action of said receiver acting thereon, to accomodate relative rotation between said locking element and said bolt means.
 9. A firearm according to claim 3 and further including a latch pivotally carried by a pivot pin in a recess of said bolt means; said neck means carrying a slot; spring means for pivoting said latch into said slot with said bolt means in an open position to lock said bolt means and saId locking element against relative rotation; said latch being disposed out of said slot in a closed position of said bolt through the action of said receiver acting thereon, to accomodate relative rotation between said locking element and said bolt means.
 10. A firearm comprising: receiver means including locking recess means; barrel means secured to said receiver means; bolt means slidably mounted in said receiver means; at least one spreader tang carried by said bolt means and arranged for shifting movement between: a locking position wherein a portion of said spreader tang is disposed in said recess means to lock said bolt means against axial movement, and a non-locking position wherein said spreader tang is free of said locking recess means; and tang-operating means rotatable relative to said bolt means and being arranged to shift said bolt means axially; said tang-operating means including means for shifting said spreader tang into said locking position in response to rotation of said tang-operating means in one direction.
 11. A firearm according to claim 10 wherein said means for shifting comprises a rotary cam surface carried by said tang-operating means.
 12. A firearm according to claim 10 and further including means for engaging and moving said spreader tang from said locking position to said unlocking position in response to rotation of said tang-operating means in the opposite direction.
 13. A firearm according to claim 12 wherein said means for engaging and moving comprises an auxiliary rotary cam surface carried by said tang-operating means.
 14. A firearm comprising: receiver means including locking recess means; barrel means secured to said receiver means; bolt means slidably mounted in said receiver means; at least one spreader tang carried by said bolt means and arranged for shifting movement between; a locking position wherein a portion of said spreader tang is disposed in said recess means to lock said bolt means against axial movement in said receiver means, and a non-locking position wherein said spreader tang is free of said locking recess means; and tang operating means mounted for rotation relative to said tang and including: first cam surface means for engaging and shifting said spreader tang into said locking position in response to rotation of said tang operating means relative to said tang in a first direction; and second cam surface means for engaging and shifting said spreader tang into said non-locking position in response to rotation of said tang operating means relative to said tang in a second direction opposed to said first direction. 